Structures, such as mobile homes, movable storage units, and cargo containers, which contain long support beams on their underside can suffer substantial structural damage from earthquakes. Typically, mobile homes or prefabricated home units contain at least two longitudinal metal beams which provide structural support for the floor of the home and also are needed when the structure is transported on a highway.
Frequently, the home is placed on a lot, and leveling jacks are positioned underneath the home and in contact with the longitudinal support beam and ground or pad, typically poured concrete.
During an earthquake, leveling jacks can collapse or vibration can cause the mobile home to move off the leveling jacks.
The longitudinal beams on the underside of the mobile home can be I-beams or C-beams or fabricated channels. The leveling jacks are typically a pier structure comprising a lower cement pylon in contact with the ground or pad, and an upper leveling screw which is in contact with the bottom of the metal beams.
Prior art efforts to provide an earthquake resistant support are shown in U.S. Pat. Nos. 4,864,785; 4,562,673; 4,546,581; 4,522,000; 4,417,426; 4,373,307; 4,348,843; 4,261,149; 2,344,383; 3,751,866; and 3,830,024.
In general, the prior art supports are complex and costly to fabricate and install, are susceptible to bending or buckling, and do not adequately compensate for the lateral motion of the mobile home. Many of the prior art supports are primarily constructed of metals which are susceptible to corrosion in the environment found under mobile homes. Many of the prior art structures cannot obtain governmental approval, such as the registration required by the Department of Housing and Community Development in the State of California.
The present invention provides a relatively simple structure comprising cribbed piers and crossed main beams and can provide effective support to minimize or eliminate damage to the mobile home from earthquake tremors and is economical and simple to construct and install. The present invention is an earthquake support for a structure having at least two bottom beams on the underside of the structure, where each bottom beam extends for a sufficient length of the structure to provide structural support for the underside, or floor, of the structure, particularly where the structure is designed to be transported on a public highway. Such structures include mobile homes, prefabricated housing units, containers and storage sheds.
The cribbed pier and crossed main beam structure of the present invention provides better earthquake support than do the stacked members of U.S. Pat. No. 4,864,785.